Research on bending-torsional coupling failure of large-scale wind turbine blades in the Engineering Thermophysics Institute

In the trend of large-scale development of wind turbines, the blades have become more slender and their torsional frequencies have continuously decreased. During the operation of large blades, the low-order bending modes often couple with the torsional modes, and the force forms of the blades are more complex, which poses new challenges for the safety and reliability of the blade structure. Focusing on the issue of structural strength of large blades, the current international academic research generally considers the ultimate structural response of the blade under bending loads. In terms of research methods, the local strain measurement and observation of damage phenomena are also the main research findings. Controversy is widespread.

To address this issue, researchers at the Research Institute of Engineering Thermophysics of the Chinese Academy of Sciences' Wind Energy Research and Development (Experimental) Center have systematically analyzed the theoretical analysis and thorough experimental design to establish a quantitative cross-scale correlation between macroscopic structural damage and microscopic material damage characteristics. On this basis, the ultimate failure test of the full-scale structure under the coupled flexural-to-torsional structure of the first large-scale blade structure was carried out, and the three-dimensional nonlinear solid mechanics phenomenon of geometric nonlinearity, material nonlinearity, and state (contact) nonlinearity were fully revealed. Strong Coupling Interactions in Structural Destruction of Large Blades . Through this study, the researchers clarified that the flattening of the hollow section, the Brazier effect, is not the dominant factor in the destruction of large-scale blade structures. It is pointed out that the nonlinear buckling of the large-scale wind blade structure is an essential factor driving the entire failure process, while the contact nonlinearity is It is an important external condition to determine the vane failure position and failure strength. At the same time, the study also found that a small torsional load will also have an important impact on the failure mode and post-buckling response of large-scale blade structures, and provide an improvement for large-scale blade structure design methods. An important theoretical basis.

Academic achievements were published in "Composite Structures" and the research work was supported by the National Natural Science Foundation of China (51405468) and the National High-Tech Research and Development Program "863" Project (2012AA051303).